Semiconductor device

ABSTRACT

A semiconductor device includes a semiconductor substrate, a transistor, and a first harmonic termination circuit. The transistor is formed at the semiconductor substrate. The transistor amplifies an input signal supplied to an input end and outputs an amplified signal through an output end. The first harmonic termination circuit attenuates a harmonic component included in the amplified signal. The first harmonic termination circuit is formed at the semiconductor substrate such that one end of the first harmonic termination circuit is connected to the output end of the transistor and the other end of the first harmonic termination circuit is connected to a ground end of the transistor.

This application claims priority from Japanese Patent Application No.2017-204492 filed on Oct. 23, 2017. The content of this application isincorporated herein by reference in its entirety.

BACKGROUND

The present disclosure relates to semiconductor devices. In potableterminals using a communication network for cellular phones, a poweramplifier module for amplifying electric power of a radio frequency (RF)signal to be transmitted to a base station is used. In such poweramplifier modules, a harmonic termination circuit is used to attenuate aharmonic component of an amplified signal output from an amplifier (asignal having a frequency that is integral multiple of a fundamentalfrequency of an amplified signal). For example, in U.S. Pat. No.8,983,406, a power amplifier module in which a harmonic terminationcircuit of an output matching circuit is configured to be provided at apad different from that for fundamental wave output is disclosed.

However, it has been newly found by the inventors that with aconfiguration in which a harmonic termination circuit is grounded at amodule substrate on which a semiconductor substrate is mounted,characteristics of a power amplifier module are deteriorated by theharmonic termination circuit. That is, in the case of wire-bondingmounting, variations in harmonic termination characteristics are causedby variations in the shape of bond wires. Furthermore, in the case offlip-chip mounting, harmonic termination characteristics aredeteriorated by loss in output at a bump. Furthermore, in the case wherean outer electrode for external connection is provided at the harmonictermination circuit, an electrostatic discharge (ESD) protection elementto protect the harmonic termination circuit is required. The voltageamplitude at output of an amplifier is large, and therefore, it isdifficult to add the ESD protection element while the output beingmaintained at a certain level.

BRIEF SUMMARY

Accordingly, the present disclosure provides a semiconductor device inwhich deterioration in characteristics by a harmonic termination circuitis reduced.

According to embodiments of the present disclosure, a semiconductordevice includes a semiconductor substrate; a transistor that amplifiesan input signal supplied to an input end and outputs an amplified signalthrough an output end, the transistor being formed at the semiconductorsubstrate; and a first harmonic termination circuit to attenuate aharmonic component included in the amplified signal, the first harmonictermination circuit being formed at the semiconductor substrate suchthat one end of the first harmonic termination circuit is connected tothe output end of the transistor and the other end of the first harmonictermination circuit is connected to a ground end of the transistor.

According to the present disclosure, a semiconductor device in whichdeterioration in characteristics by a harmonic termination circuit isreduced can be provided.

Other features, elements, characteristics and advantages of the presentdisclosure will become more apparent from the following detaileddescription of embodiments of the present disclosure with reference tothe attached drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a circuit diagram of a power amplifier circuit mounted on asemiconductor device according to a first embodiment of the presentdisclosure;

FIG. 2 is a schematic plan view of a semiconductor device according tothe first embodiment of the present disclosure;

FIG. 3 is a schematic plan view of a semiconductor device according to acomparative example;

FIG. 4 is a graph illustrating results of simulation of a gain;

FIG. 5 is a graph illustrating results of simulation of P2dB;

FIG. 6 is a graph illustrating results of simulation of power-addedefficiency (PAE);

FIG. 7 is a schematic plan view of a semiconductor device according to amodification of the first embodiment of the present disclosure;

FIG. 8 is a schematic plan view of a semiconductor device according to asecond embodiment of the present disclosure; and

FIG. 9 is a schematic plan view of a semiconductor device according to athird embodiment of the present disclosure.

DETAILED DESCRIPTION

Embodiments of the present disclosure will be explained with referenceto accompanying drawings. In the drawings, components referred to withthe same reference signs have the same or similar configurations.

First Embodiment

FIG. 1 is a circuit diagram of a power amplifier circuit mounted on asemiconductor device according to a first embodiment of the presentdisclosure. A power amplifier circuit 1 illustrated in FIG. 1 is acircuit that amplifies an input signal, which is an RF signal, andoutputs an amplified signal. For example, the frequency of an inputsignal ranges from about several hundred MHz to about several GHz.

The power amplifier circuit 1 includes, for example, a transistor Q1, aharmonic termination circuit HT1, an inductor L10, and a parasiticinductor L20.

The transistor Q1 configures a power amplifier that amplifies an RFsignal. In the first embodiment, the transistor Q1 is a bipolartransistor such as a heterojunction bipolar transistor (HBT) or thelike. The transistor may be a different type of transistor such as ametal-oxide-semiconductor field-effect transistor (MOSFET) or the like.

An input signal RFin is supplied to a base (input end) of the transistorQ1. A power supply voltage Vcc is supplied to a collector (output end)of the transistor Q1 via the inductor L10. An emitter (ground end) ofthe transistor Q1 is connected to the ground via the parasitic inductorL20. The transistor Q1 amplifies the input signal RFin and outputs anamplified signal RFout through the collector. Although not illustratedin FIG. 1, a bias current or voltage is supplied from a bias circuit tothe base of the transistor Q1. The number of transistors Q1 included inthe power amplifier circuit 1 is not limited to one. A plurality oftransistors Q1 may be included in the power amplifier circuit 1.

The inductor L10 is a choke inductor that reduces leakage of an RFsignal toward a power supply. For explanation, the inductor L10 isrepresented by a symbol indicating an inductance element. However, theinductor L10 is not necessarily an inductance element. The inductor L10may be a different element containing an inductance component. Adifferent element containing an inductance component is, for example, abond wire formed by wire bonding or the like.

The parasitic inductor L20 is an element containing an inductancecomponent and is, for example, a parasitic inductance of a semiconductorsubstrate at which the transistor Q1 is formed and a parasiticinductance such as a wire formed at a module substrate for mounting thesemiconductor substrate.

The harmonic termination circuit HT1 is a circuit that attenuates aharmonic component contained in the amplified signal RFout output fromthe collector of the transistor Q1. Specifically, the harmonictermination circuit HT1 is a series resonance circuit including acapacitor C1 and an inductor L1 that are connected in series.

One end of the capacitor C1 is connected to the collector of thetransistor Q1, and the other end of the capacitor C1 is connected to oneend of the inductor L1. The other end of the inductor L1 is connected tothe emitter of the transistor Q1. The inductor L1 is an elementcontaining an inductance component and is, for example, a wire formedinside the semiconductor substrate at which the transistor Q1 is formed.The number of harmonic termination circuits is not limited to one.Another harmonic termination circuit may be provided in parallel to theharmonic termination circuit HT1.

FIG. 2 is a schematic plan view of a semiconductor device 100A accordingto the first embodiment of the present disclosure.

The semiconductor device 100A includes, for example, a semiconductorsubstrate 110, a transistor region 120, a harmonic termination circuitHT1 a (first harmonic termination circuit), and a harmonic terminationcircuit HT1 b (second harmonic termination circuit).

The semiconductor substrate 110 is a semiconductor substrate thatincludes a main surface 110P having substantially a rectangular shapethat is parallel to an XY plane on which various elements are to bemounted. The semiconductor substrate 110 is mounted on a modulesubstrate, which is not illustrated in FIG. 2, with bumps 130 a, 130 b,130 c, 130 d, and the like interposed therebetween by so-calledflip-chip mounting.

The transistor region 120 is a region in which the transistor Q1 isformed. In the first embodiment, the transistor Q1 is a multi-fingertransistor including a plurality of fingers (unit transistors) that areconnected in parallel to each other. The plurality of fingers of thetransistor Q1 formed in the transistor region 120 are arrangedsymmetrically with respect to a median line 120M that is parallel to a Yaxis. The transistor region 120 includes a first transistor region 120 athat is located in an X-axis negative direction relative to the medianline 120M and a second transistor region 120 b that is located in anX-axis positive direction relative to the median line 120M.

The emitter of the transistor Q1 formed in the first transistor region120 a is electrically connected to the bump 130 a. The emitter of thetransistor Q1 formed in the second transistor region 120 b iselectrically connected to the bump 130 b. To mount the semiconductorsubstrate 110 on the module substrate, the bumps 130 a and 130 b areelectrically connected to ground electrodes formed at the modulesubstrate. Accordingly, the emitter of each of the transistors Q1 isconnected to the ground.

The collector of the transistor Q1 formed in the first transistor region120 a is electrically connected to the bump 130 c. The collector of thetransistor Q1 formed in the second transistor region 120 b iselectrically connected to the bump 130 d. To mount the semiconductorsubstrate 110 on the module substrate, the bumps 130 c and 130 d areelectrically connected to wires formed at the module substrate.

The harmonic termination circuit HT1 a is a circuit that attenuates aharmonic component contained in an amplified signal output from thecollector of the transistor Q1 formed in the first transistor region 120a, as explained above with reference to FIG. 1. Specifically, theharmonic termination circuit HT1 a is a series resonance circuit thatincludes a capacitor C1 a (first capacitor) and an inductor L1 a (firstinductor) that are connected in series. The inductor L1 a is, forexample, a wire containing an inductance component provided at thesemiconductor substrate 110.

One end of the harmonic termination circuit HT1 a is connected to theoutput end of the transistor Q1 formed in the first transistor region120 a on the semiconductor substrate 110. Furthermore, the other end ofthe harmonic termination circuit HT1 a is connected to the ground end ofthe transistor Q1 formed in the first transistor region 120 a on thesemiconductor substrate 110. Specifically, one end of the capacitor C1 ais connected to the collector of the transistor Q1 formed in the firsttransistor region 120 a, and the other end of the capacitor C1 a isconnected to one end of the inductor L1 a. The other end of the inductorL1 a is connected to the bump 130 a, which is electrically connected tothe ground electrode at the module substrate, as described above.

In a similar manner, the harmonic termination circuit HT1 b is a circuitthat attenuates a harmonic component contained in an amplified signaloutput from the collector of the transistor Q1 formed in the secondtransistor region 120 b, as described above with reference to FIG. 1.Specifically, the harmonic termination circuit HT1 b is a seriesresonance circuit that includes a capacitor C1 b (second capacitor) andan inductor L1 b (second inductor) that are connected in series. Theinductor L1 b is, for example, a wire containing an inductance componentprovided at the semiconductor substrate 110.

One end of the harmonic termination circuit HT1 b is connected to theoutput end of the transistor Q1 formed in the second transistor region120 b on the semiconductor substrate 110. Furthermore, the other end ofthe harmonic termination circuit HT1 b is connected to the ground end ofthe transistor Q1 formed in the second transistor region 120 b on thesemiconductor substrate 110. Specifically, one end of the capacitor C1 bis connected to the collector of the transistor Q1 formed in the secondtransistor region 120 b, and the other end of the capacitor C1 b isconnected to one end of the inductor L1 b. The other end of the inductorL1 b is connected to the bump 130 b, which is electrically connected tothe ground electrode at the module substrate, as described above.

The harmonic termination circuit HT1 a and the harmonic terminationcircuit HT1 b are arranged symmetrically with respect to the median line120M described above. In other words, the harmonic termination circuitHT1 a and the harmonic termination circuit HT1 b are arrangedsymmetrically with respect to the transistor region 120. Specifically,the capacitor C1 a and the capacitor C1 b are arranged symmetricallywith respect to the median line 120M (transistor region 120), and theinductor L1 a and the inductor L1 b are arranged symmetrically withrespect to the median line 120M (transistor region 120).

FIG. 3 is a schematic plan view of a semiconductor device 1000 accordingto a comparative example. Configuration features of the semiconductordevice 1000 according to the comparative example that are different fromthose of the semiconductor device 100A according to the first embodimentof the present disclosure will be explained below. Explanation for thesame configuration features as those of the semiconductor device 100Awill be omitted in an appropriate manner.

The semiconductor device 1000 further includes bumps 130 e and 130 f, inaddition to the bumps 130 a, 130 b, 130 c, and 130 d. To mount thesemiconductor substrate 110 on the module substrate, the bumps 130 e and130 f are electrically connected to ground electrodes formed at themodule substrate.

The semiconductor device 1000 includes harmonic termination circuitsHT10 a and HT10 b. The harmonic termination circuit HT10 a is a seriesresonance circuit that includes the capacitor C1 a and an inductor L10 athat are connected in series. The harmonic termination circuit HT10 b isa series resonance circuit that includes the capacitor C1 b and aninductor L10 b that are connected in series.

One end of the harmonic termination circuit HT10 a is connected to theoutput end of the transistor Q1 formed in the first transistor region120 a. However, the other end of the harmonic termination circuit HT10 ais not connected to the ground end of the transistor Q1 formed in thefirst transistor region 120 a but is connected to the ground electrodeat the module substrate with the bump 130 e interposed therebetween.Specifically, one end of the capacitor C1 a is connected to thecollector of the transistor Q1 formed in the first transistor region 120a, and the other end of the capacitor C1 a is connected to one end ofthe inductor L10 a. The other end of the inductor L10 a is connected tothe bump 130 e, which is electrically connected to the ground electrodeat the module substrate, as described above.

In a similar manner, one end of the harmonic termination circuit HT10 bis connected to the output end of the transistor Q1 formed in the secondtransistor region 120 b. However, the other end of the harmonictermination circuit HT10 b is not connected to the ground end of thetransistor Q1 formed in the second transistor region 120 b but isconnected to the ground electrode at the module substrate with the bump130 f interposed therebetween. Specifically, one end of the capacitor C1b is connected to the collector of the transistor Q1 formed in thesecond transistor region 120 b, and the other end of the capacitor C1 bis connected to one end of the inductor L10 b. The other end of theinductor L10 b is connected to the bump 130 f, which is electricallyconnected to the ground electrode at the module substrate, as describedabove.

FIG. 4 is a diagram illustrating results of simulation of a gain. InFIG. 4, the horizontal axis represents an output level (dBm) of an RFsignal, and the vertical axis represents a gain (dB). In FIG. 4, a solidline represents results of simulation of a gain of the semiconductordevice 100A according to the first embodiment of the present disclosure,and a broken line represents results of simulation of a gain of thesemiconductor device 1000 according to the comparative example. In eachof the semiconductor device 100A and the semiconductor device 1000, thefrequency of an RF signal is about 3,500 MHz.

As is clear from FIG. 4, the linearity of the gain of the semiconductordevice 100A is excellent compared to that of the semiconductor device1000 according to the comparative example. In particular, the gain ofthe semiconductor device 1000 significantly drops at a relatively earlystage when the output level increases. In contrast, a significant changedoes not occur in the gain of the semiconductor device 100A up to about30 dBm, and it is thus clear that linearity of the semiconductor device100A is maintained.

FIG. 5 is a diagram illustrating results of simulation of P2dB. Herein,P2dB represents an output level at a point to which ideal linear outputcharacteristics are decreased by about 2 dB. In FIG. 5, the horizontalaxis represents a frequency (Hz) of an RF signal, and the vertical axisrepresents P2dB (dBm). In FIG. 5, a solid line represents results ofsimulation of P2dB of the semiconductor device 100A according to thefirst embodiment of the present disclosure, and a broken line representsresults of simulation of P2dB of the semiconductor device 1000 accordingthe comparative example.

As is clear from FIG. 5, P2dB of the semiconductor device 100A in afrequency band from about 3.40 GHz to about 3.60 GHz is improved,compared to the semiconductor device 1000.

FIG. 6 is a diagram illustrating results of simulation of a power-addedefficiency (PAE). In FIG. 6, the horizontal axis represents a frequency(Hz) of an RF signal, and the vertical axis represents a PAE (%). InFIG. 6, a solid line represents results of simulation of the PAE of thesemiconductor device 100A according to the first embodiment of thepresent disclosure, and a broken line represents results of simulationof the PAE of the semiconductor device 1000 according to the comparativeexample.

As is clear from FIG. 6, the PAE of the semiconductor device 100A in afrequency band from about 3.40 GHz to about 3.60 GHz is improved,compared to the semiconductor device 1000.

As described above, in the semiconductor device 100A, one ends of theharmonic termination circuits HT1 a and HT1 b are connected to theoutput ends of the transistors Q1, and the other ends of the harmonictermination circuits HT1 a and HT1 b are connected to the ground ends ofthe transistors Q1. Thus, in the semiconductor device 100A, the otherends of the harmonic termination circuits HT1 a and HT1 b are connectedto the bumps 130 a and 130 b, which are connected to the ground ends ofthe transistors, and therefore, parasitic resistance components of thebumps 130 a and 130 b are smaller than parasitic resistances of thebumps 130 e and 130 f. Consequently, loss in the output of thesemiconductor device 100A can be reduced. Furthermore, in thesemiconductor device 100A, each harmonic termination circuit is closedwithin a chip, and therefore, no external electrode is needed.Consequently, there is no need to add an ESD protection element toprotect the harmonic termination circuit.

Furthermore, the semiconductor device 100A includes the plurality ofharmonic termination circuits HT1 a and HT1 b. Therefore, in thesemiconductor device 100A, variations in the length of wires forconnecting the collectors of the transistors Q1 formed in the transistorregion 120 and the harmonic termination circuits are reduced.

Furthermore, the harmonic termination circuit HT1 a and the harmonictermination circuit HT1 b of the semiconductor device 100A are arrangedsymmetrically with respect to the transistor region 120. Therefore, inthe semiconductor device 100A, variations in the length of wires forconnecting the collectors of the transistors Q1 formed in the transistorregion 120 and the harmonic termination circuits are reduced.

Modification of First Embodiment

FIG. 7 is a schematic plan view of a semiconductor device 200A accordingto a modification of the first embodiment of the present disclosure.

The semiconductor device 200A includes, for example, a semiconductorsubstrate 210, a transistor region 220, and harmonic terminationcircuits HT2 a and HT2 b.

The semiconductor substrate 210 is a semiconductor substrate thatincludes a main surface 210P having substantially a rectangular shapethat is parallel to an XY plane on which various elements are to bemounted. A terminal provided at the semiconductor substrate 210 isconnected with a terminal provided at a module substrate, which is notillustrated in FIG. 7, by a metal wire, by so-called wire-bondingmounting, so that the semiconductor substrate 210 is mounted on themodule substrate.

The transistor region 220 is a region in which the transistor Q1 isformed. In the first embodiment, the transistor Q1 is a multi-fingertransistor including a plurality of fingers (unit transistors) that areconnected in parallel to each other. The plurality of fingers of thetransistor Q1 formed in the transistor region 220 are arrangedsymmetrically with respect to a median line 220M that is parallel to a Yaxis. The transistor region 220 includes a first transistor region 220 athat is located in an X-axis negative direction relative to the medianline 220M and a second transistor region 220 b that is located in anX-axis positive direction relative to the median line 220M.

In the semiconductor substrate 210, vias 230 a 1, 230 a 2, 230 a 3, 230a 4, 230 b 1, 230 b 2, 230 b 3, and 230 b 4 are formed. Emitters of thetransistor Q1 formed in the first transistor region 220 a areelectrically connected to the vias 230 a 1, 230 a 2, 230 a 3, and 230 a4. Furthermore, emitters of the transistor Q1 formed in the secondtransistor region 220 b are electrically connected to the vias 230 b 1,230 b 2, 230 b 3, and 230 b 4. The vias 230 a 1, 230 a 2, 230 a 3, 230 a4, 230 b 1, 230 b 2, 230 b 3, and 230 b 4 are connected to emitterterminals, which are not illustrated in FIG. 7, provided at thesemiconductor substrate 210. To mount the semiconductor substrate 210 onthe module substrate, the emitter terminals are electrically connectedto ground electrodes formed at the module substrate. Accordingly, theemitters of the transistors Q1 are connected to the ground. Vias may beformed on the median line 220M.

At the semiconductor substrate 210, collector terminals 240 a, 240 b,240 c, and 240 d are formed. Collectors of the transistor Q1 formed inthe first transistor region 220 a are electrically connected to thecollector terminals 240 a and 240 b. Collectors of the transistor Q1formed in the second transistor region 220 b are electrically connectedto the collector terminals 240 c and 240 d. To mount the semiconductorsubstrate 210 on the module substrate, the collector terminals 240 a,240 b, 240 c, and 240 d are electrically connected to wires formed atthe module substrate.

As explained above with reference to FIG. 1, the harmonic terminationcircuit HT2 a is a circuit that attenuates a harmonic componentcontained in an amplified signal output from the collector of thetransistor Q1 formed in the first transistor region 220 a. Specifically,the harmonic termination circuit HT2 a is a series resonance circuitthat includes a capacitor C2 a and an inductor L2 a that are connectedin series. The inductor L2 a is a wire that contains an inductancecomponent provided at the semiconductor substrate 210.

One end of the harmonic termination circuit HT2 a is connected to theoutput end of the transistor Q1 formed in the first transistor region220 a, and the other end of the harmonic termination circuit HT2 a isconnected to the emitters of the transistor Q1 formed in the firsttransistor region 220 a and the vias 230 a 1 to 230 a 4. Specifically,one end of the capacitor C2 a is connected to the collectors of thetransistor Q1 formed in the first transistor region 220 a, and the otherend of the capacitor C2 a is connected to one end of the inductor L2 a.The other end of the inductor L2 a is connected to the vias 230 a 1, 230a 2, 230 a 3, and 230 a 4, which are connected to the emitter terminals,which are not illustrated in FIG. 7, provided at the semiconductorsubstrate 210, as described above.

In a similar manner, the harmonic termination circuit HT2 b is a circuitthat attenuates a harmonic component contained in an amplified signaloutput from the collector of the transistor Q1 formed in the secondtransistor region 220 b, as explained above with reference to FIG. 1.Specifically, the harmonic termination circuit HT2 b is a seriesresonance circuit that includes a capacitor C2 b and an inductor L2 bthat are connected in series. The inductor L2 b is a wire that containsan inductance component provided at the semiconductor substrate 210.

One end of the harmonic termination circuit HT2 b is connected to theoutput end of the transistor Q1 formed in the second transistor region220 b, and the other end of the harmonic termination circuit HT2 b isconnected to the emitters of the transistor Q1 formed in the secondtransistor region 220 b and the vias 230 b 1 to 230 b 4. Specifically,one end of the capacitor C2 b is connected to the collectors of thetransistor Q1 formed in the second transistor region 220 b, and theother end of the capacitor C2 b is connected to one end of the inductorL2 b. The other end of the inductor L2 b is connected to the vias 230 b1, 230 b 2, 230 b 3, and 230 b 4, which are connected to the emitterterminals, which are not illustrated in FIG. 7, provided at thesemiconductor substrate 210, as described above.

As described above, in the semiconductor device 200A, one ends of theharmonic termination circuits HT2 a and HT2 b are connected to theoutput ends of the transistors Q1, and the other ends of the harmonictermination circuits HT2 a and HT2 b are connected to the ground ends ofthe transistors Q1. Therefore, there is no need to connect the harmonictermination circuits to the module substrate by bond wires or the like,and deterioration in characteristics caused by variations in the shapeof bond wires is reduced.

Second Embodiment

FIG. 8 is a schematic plan view of a semiconductor device 100B accordingto a second embodiment of the present disclosure. Configuration featuresof the semiconductor device 100B according to the second embodiment ofthe present disclosure that are different from those of thesemiconductor device 100A according to the first embodiment of thepresent disclosure will be explained below. Explanation forconfiguration features of the semiconductor device 100B that are thesame as those of the semiconductor device 100A will be omitted in anappropriate manner.

The semiconductor device 100B further includes an inductor L3 (thirdinductor). The inductor L3 is formed at the semiconductor substrate 110such that a portion between the capacitor C1 a and the inductor L1 athat are included in the harmonic termination circuit HT1 a is connectedwith a portion between the capacitor C1 b and the inductor L1 b that areincluded in the harmonic termination circuit HT1 b. The inductor L3 is,for example, a wire that contains an inductance component provided atthe semiconductor substrate 110.

With the above configuration of the semiconductor device 100B, even ifvariations occur in the length of lines of the inductors L1 a and L1 b,variations in the impedance of the harmonic termination circuits HT1 aand HT1 b are reduced.

Third Embodiment

FIG. 9 is a schematic plan view of a semiconductor device 100C accordingto a third embodiment of the present disclosure. Configuration featuresof the semiconductor device 100C according to the third embodiment ofthe present disclosure that are different from those of thesemiconductor device 100B according to the second embodiment of thepresent disclosure will be explained below. Explanation forconfiguration features of the semiconductor device 100C that are thesame as those of the semiconductor device 100B will be omitted in anappropriate manner.

The semiconductor device 100C further includes a capacitor C2 (thirdcapacitor). The capacitor C2 is formed at the semiconductor substrate110 such that the collectors (output ends) of the transistors Q1 areconnected with the inductor L3. The capacitor C2 is, for example,connected at a halfway point along the line of the inductor L3.

With the above configuration of the semiconductor device 100C, even ifvariations occur in the length of lines of the inductors L1 a and L1 b,variations in the impedance of the harmonic termination circuits HT1 aand HT1 b are further reduced.

Other Embodiments

A semiconductor device according to each of the embodiments describedabove includes two harmonic termination circuits that are arrangedsymmetrically with respect to a transistor region. However, the numberof harmonic termination circuits included in a semiconductor device isnot limited to two. One harmonic termination circuit or three or moreharmonic termination circuits may be included in a semiconductor device.For example, a semiconductor device may include two or more (forexample, two, three, four, or the like) pairs each including twoharmonic termination circuits that are arranged symmetrically withrespect to a transistor region. Furthermore, harmonic terminationcircuits may not be arranged symmetrically with respect to a transistorregion.

Exemplary embodiments of the present disclosure have been describedabove. In the semiconductor device 100A, one ends of the harmonictermination circuits HT1 a and HT1 b are connected to the output ends ofthe transistors Q1, and the other ends of the harmonic terminationcircuits HT1 a and HT1 b are connected to the ground ends of thetransistors Q1. Therefore, in the semiconductor device 100A, loss inoutput at a bump is reduced. Furthermore, in the semiconductor device100A, there is no need to add an ESD protection element for a harmonictermination circuit.

Furthermore, the semiconductor device 100A includes the plurality ofharmonic termination circuits HT1 a and HT1 b. Therefore, in thesemiconductor device 100A, variations in the length of wires forconnecting collectors of the transistors Q1 included in the transistorregion 120 with the harmonic termination circuits are reduced.

Furthermore, the harmonic termination circuit HT1 a and the harmonictermination circuit HT1 b of the semiconductor device 100A are arrangedsymmetrically with respect to the transistor region 120. Therefore, inthe semiconductor device 100A, variations in the length of wires forconnecting the collectors of the transistors Q1 included in thetransistor region 120 with the harmonic termination circuits arereduced.

Furthermore, in the semiconductor device 200A, the other ends of theharmonic termination circuits HT2 a and HT2 b are connected to theground lines of the transistors Q1. Therefore, there is no need toconnect the harmonic termination circuits to the module substrate bybond wires or the like, and deterioration in characteristics caused byvariations in the shape of bond wires is reduced.

Furthermore, the semiconductor device 100B further includes the inductorL3 (third inductor). The inductor L3 is formed at the semiconductorsubstrate 110 such that a portion between the capacitor C1 a and theinductor L1 a that are included in the harmonic termination circuit HT1a is connected with a portion between the capacitor C1 b and theinductor L1 b that are included in the harmonic termination circuit HT1b. Therefore, in the semiconductor device 100B, even if variations occurin the length of lines of the inductors L1 a and L1 b, variations in theimpedance of the harmonic termination circuits HT1 a and HT1 b arereduced.

Furthermore, the semiconductor device 100C further includes thecapacitor C2 (third capacitor). The capacitor C2 is formed at thesemiconductor substrate 110 such that the collectors (output ends) ofthe transistors Q1 are connected with the inductor L3. Therefore, in thesemiconductor device 100C, even if variations occur in the length oflines of the inductors L1 a and L1 b, variations in the impedance of theharmonic termination circuits HT1 a and HT1 b are further reduced.

The embodiments described above are provided for easier understanding ofthe present disclosure and are not intended to limit the presentdisclosure. Components included in each embodiment and arrangements,materials, conditions, shapes, sizes, and the like of the componentsincluded in each embodiment are not limited to those illustrated in theembodiment and may be changed in an appropriate manner. Furthermore,configurations described in different embodiments may be partiallyreplaced or combined with each other.

While embodiments of the disclosure have been described above, it is tobe understood that variations and modifications will be apparent tothose skilled in the art without departing from the scope and spirit ofthe disclosure. The scope of the disclosure, therefore, is to bedetermined solely by the following claims.

What is claimed is:
 1. A semiconductor device comprising: asemiconductor substrate; a transistor that amplifies an input signalsupplied to an input end and outputs an amplified signal through anoutput end, the transistor being formed at the semiconductor substrate;and a first harmonic termination circuit configured to attenuate aharmonic component of the amplified signal, the first harmonictermination circuit being formed on the semiconductor substrate suchthat a first end of the first harmonic termination circuit is connectedto the output end of the transistor and a second end of the firstharmonic termination circuit is connected to a third end of thetransistor, the third end being extended toward ground, wherein thetransistor is a multi-finger transistor having a plurality of unittransistors, the first harmonic termination circuit being configured toattenuate a harmonic component of an amplified signal output from anoutput end of a first unit transistor, and being connected between theoutput end and a ground end of the first unit transistor, wherein thesemiconductor device further comprises a second harmonic terminationcircuit configured to attenuate a harmonic component of an amplifiedsignal output from an output end of a second unit transistor, the secondharmonic termination circuit being formed on the semiconductor substratesuch that a first end of the second harmonic termination circuit isconnected to the output end of the second unit transistor and a secondend of the second harmonic termination circuit is connected to a groundend of the second unit transistor, and wherein the first harmonictermination circuit and the second harmonic termination circuit arearranged symmetrically with respect to a region of the semiconductorsubstrate in which the first and second unit transistors are formed. 2.The semiconductor device according to claim 1, wherein the firstharmonic termination circuit comprises a first capacitor and a firstinductor that are connected in series, and wherein the second harmonictermination circuit comprises a second capacitor and a second inductorthat are connected in series.
 3. The semiconductor device according toclaim 2, further comprising: a third inductor that is formed on thesemiconductor substrate such that a portion between the first capacitorand the first inductor is connected to a portion between the secondcapacitor and the second inductor via the third inductor.
 4. Thesemiconductor device according to claim 3, further comprising: a thirdcapacitor that is formed on the semiconductor substrate such that theoutput ends of the first and second unit transistors are connected tothe third inductor.
 5. The semiconductor device according to claim 4,wherein the output ends of the first and second unit transistors areconnected to the third inductor via the third capacitor.
 6. Thesemiconductor device according to claim 1, wherein the first harmonictermination circuit and the second harmonic termination circuit arearranged symmetrically about a median line of the semiconductorsubstrate.
 7. The semiconductor device according to claim 1, wherein thetransistor is a heterojunction bipolar transistor.
 8. The semiconductordevice according to claim 2, wherein the first inductor and the secondinductor are formed as a wire or wires in or on the semiconductorsubstrate.